The invention relates to a self-piercing blind rivet for apposing biological tissue and to a device for setting the same, especially through the instrument channel of a flexible endoscope, in order to connect layers of tissue with an adjustable contacting force.
Blind rivets are usually used to connect metal sheets, predominantly in aircraft construction. However, they can also be used for other materials, such as plastics, wood or leather. Their great advantage over other forms of rivets is that the parts to be joined have to be accessible only from one side, since there is no need for a bottom die to close the rivet. For most blind rivets, holes, which are one above the other for setting the rivet, must be drilled to start with. There are, however, also blind rivets, for example, in the EP 0 705 389 B1, which are self piercing in that they pierce the parts to be joined automatically during the setting process.
In surgery also, there are first indications of the use of blind rivets. Their applications are limited, however, mainly to fixing implants or tissue to bones, as described in U.S. Pat. No. 6,241,732 B1 or the WO 99/62418. A corneal rivet (U.S. Pat. No. 5,258,011), by means of which it is possible to close cuts in the cornea of the eye, is also worth mentioning. This rivet, however, mainly is not constructed as a blind rivet and must instead be serviced from both sides, which makes use in endoscopy difficult and requires an additional instrument.
Suturing techniques are mainly used in medicine for apposing tissue. For example, attempts have been made to develop suturing devices for minimally invasive surgery to close off tissue discontinuities when operating on the gastrointestinal tract. Since the needle can no longer be guided with the fingers here, this guidance must be taken over by grippers. However, since these grippers do not attain even approximately the freedom of movement and the movement possibilities of the hand, this suturing is very difficult, uncertain and time consuming. For this reason, different devices for automated suturing have been planned and, in some cases, put into practice. U.S. Pat. No. 6,071,289 is an example of this. However, even with such a device, the most serious disadvantage of the suturing technique, namely, the knotting of the suture, cannot be eliminated. For this purpose, either a knot is made outside of the body and pushed through the instrument channel or the suture is knotted laboriously with grippers. Accordingly, because of their complexity and the therefrom resulting overall size, it has not yet been possible to insert such devices into the instrument channels of flexible endoscopes.
Because of the disadvantages of suturing devices, clamps and clips were developed as alternatives. These consist essentially of two arms, which are connected to one another and with which the tissue can be held together, as disclosed in the German patents 299 23 545 U1 or 102 03 956 A1. Since the arms can be expanded only to a very limited extent for this purpose, it is necessary that the tissue parts, which are to be joined, be approximated with a further device before the application, so that use by means of an endoscope is prevented.
The connecting element of the US patent application 2003/0125755 is a combination of a clip and a suturing method. A clip, which is detached from a suture with pliers, hangs at the end of a needle with suture. In this way, the problem of the knot is overcome. Once again, however, it is necessary to use a further instrument, so that the instrument channel of an endoscope cannot be used by itself.
The WO 99/60931 application represents a further embodiment, which may be regarded as a blind rivet. The clip here consists of a carrier, a distal fixing element and a proximal fixing element. For the function, a connecting sleeve between the two fixing elements is also provided here. The sleeve determines the distance between the fixing elements. For this reason, the extent of the tissue approximation is fixed. It is therefore not possible to connect tissues of different or unknown thicknesses using one and the same clip. This represents a major limitation for the surgeon. Associated with this is the fact that the contacting force, with which the tissue is held together, is also not adjustable, so that the surgeon cannot gain any feeling for the quality of the connection. Moreover, the functional reliability of the clip is also a cause for concern, since a stop has not been provided for the proximal fixation element, so that it may happen that the complete clip can be pushed through the tissue and, as it were, fall out on the other side. It is also not possible here to load the clips into a magazine, that is, to set several clips consecutively with one instrument. For reloading, the whole instrument must be exchanged or, at the very least, removed from the endoscope.